It's a perfect way to determine if there is power going to your ionizer!

The Model SC-ACSN AC Sensor is a hand-held device for determining the presence or absence of AC in insulated wires, wall receptacles, fuses, junction boxes, switches and other voltage-carrying electrical systems.

It is not necessary to disconnect the system in question because no contact is required for operation and current flow is not necessary to locate voltage. Simply touch the tip to a connection point or move it along a wire. If AC voltage is present, you will hear an audible tone.